1. Field of the Invention
This invention relates to a silicone system which provides an elastomeric silicone finish and methods of preparation thereof. The silicone system is prepared from a blend of silanols and crosslinkable silicone intermediates. This silicone system can be used in combination with other known finishing agents.
2. Description of the Prior Art
Silicone products have been used extensively in the textile industry for more than twenty years as water repellents, antifoams, lubricants, softeners and the like. The most important silicone products have been dimethylpolysiloxane, used as a softener, and methylhydrogenpolysiloxane, used as the base for silicone water repellents.
These silicone products, and others, have advantages over hydrocarbon compounds, paraffin waxes and fatty acid waxes, especially in regards to processing and the ultimate properties of the treated materials. Because of these advantages organosilicon polymers as textile chemicals were explored, resulting initially in U.S. Pat. No. 2,891,920 which taught the manufacture of emulsion polymerized dimethyl polysiloxanes.
Some ten years later Weyenberg published a written reference to organosilicon polymers in textile chemicals. Journal of Polymer Science, Part C, No. 27 (1969). And more recently, the specific application of these silicones polymers as a textile finish has been made by Rooks in Textile Chemist and Colorist, Vol. 4, No. 1, January 1972. The Rooks article specifically referred to the use of silanol endblocked dimethylpolysiloxane emulsion polymers with monomeric methyltrimethoxy silanes as the crosslinker and an organo tin catalyst. The Rook article noted that the use of these ingredients in fortifying or improving the durable press performance of polyester/cellulosic blends was its most important application. However, this technology proved commercially unacceptable because of its lack of consistency under mill conditions and the occurrence of silicone spots on the fabric.
Recently, an elastomeric silicone system has been introduced as a textile finish. This system is reported to impart improved resilience and stretch, shape recovery and dimensional stability to knitted and stretched woven fabrics. This silicone system consists of three emulsion components, the components are a high molecular weight silanol fluid with a dimethylmethylhydrogen fluid correactant and a zinc 2-ethylhexonate catalyst. The system is in emulsion form, which limits the ability of formulators to add value to the component materials and is subject to critical operating conditions which if not met could result in a dangerous evolution of hydrogen.
Despite these recent advances there continues a need for a silicone system that provides a better elastomeric finish that is easier to employ and which acts as a softener by itself or can be used as a component in a durable resin bath. Additionally, the silicone system must be stable and impart formulation latitude so as to be acceptable across the spectrum of mill operations. Finally, it is important that the silicone system be easily catalyzed and preferably employ the same catalyst as found in a typical durable press resin bath.